1. Field of the Invention
This invention relates to centrifugal pumps, and more particularly is concerned with pitot pumps.
2. Brief Description of the Prior Art
Pitot pumps are a form of centrifugal pumps. Typically, a pitot pump is constructed by providing a hollow rotatable casing disposed within a suitable surrounding stationary housing. A plurality of radial ducts in the walls of the casing directs the fluid to be pumped outwardly by centrifugal force as the casing is rotated, the fluid being discharged into the interior of the rotating casing. Stationary pitot tube means in the interior of the casing intercept the rotating fluid in the casing, the ram effect forcing fluid out through the pitot tubes. Pitot pumps of this type are well known and typically are illustrated and described in U.S. Pat. No. 3,384,024 entitled "Centrifugal Pump", William L. Kind, owned by the assignee of the present invention.
The prior art apparatus includes a rotating housing and a stationary pickup tube collector arm within the rotating housing. The fluid to be pumped enters an intake manifold and passes into the rotating housing wherein the velocity of the fluid is increased. Centrifugal force induced by the rotating housing forces the fluid introduced therein to the peripheral outer extremities of the rotating housing through a plurality of discrete radial passages which are typically formed in an end wall of the rotating housing. The fluid is forced to the outlets of the radial passages from which the fluid is injected at high velocity or high pressure, if the pumping chamber is already filled with fluid, into the main pumping chamber. The velocity energy of the fluid within the pumping chamber is converted into additional energy as it jets into the pickup tube and thence to a discharge conduit. During certain portions of the pumping cycle it is desirous to permit a recirculation of the fluid being pumped. Typically, the desired recirculation of the fluid in the prior art structures has been accomplished from the pumping chamber of the rotating casing to the radial passages through a labyrinth type rotating seal means. In the event the labyrinth leakage is prevented, unacceptable pumping characteristics manifest themselves.
Also, it has been found that undesirable pumping characteristics have become apparent due to the presence of air in the pumping chamber of the rotating casing.